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Waste materials contribute to a wide range of environmental and economic problems. To minimize their effects, a safe strategy for reducing such negative impact is required. Recycling and reusing waste materials have proved to be effective measures in this respect. In this study, an eco-friendly treatment is investigated based on using waste powdered glass (WGP) and EPS beads (EPSb) as mechanical and chemical admixers in soils. For this purpose, Atterberg limit, standard proctor, free swell, and unconfined compression tests are performed on soil samples with different ratios of waste materials at their optimum moisture contents. The obtained test results indicate that adding WGP to cohesive soils increases the unconfined compressive strength (UCS) and reduces free swell (FS). In contrast, using EPSb reduces both FS and UCS of the treated soil samples. An optimum combination of both waste materials is determined for the improvement of the properties of high plasticity clay used in this study. Furthermore, multiple linear regression (MLR) and artificial neural network (ANN) methods are used to predict the FS and UCS of the clayey soils based on the data obtained here and the experimental test results reported in the literature. Once the FS and UCS values of untreated soil and additive percentages are defined as independent variables, both methods are shown to predict the FS and UCS values of the treated soil samples on a satisfactory level with the coefficient of correlation ( R 2 ) values greater than 0.926. Additionally, when only the index properties (liquid limit, plastic limit, and plasticity index) of the soil samples with waste materials are used as dependent variables, the R 2 values obtained by the ANN method are 0.968 and 0.974 for FS and UCS, respectively. The results of the untreated soil samples' FS and UCS tests are known, and the linear regression and ANN techniques yield similar results. Lastly, the ANN method is used to predict the FS and UCS of the treated samples in accordance to the limited predictors (e.g., only the Atterberg limits of the soil sample). [ABSTRACT FROM AUTHOR]

In recent years, individuals have begun to pay more attention to non-traditional stabilizers due to the problems connected with traditional stabilizers. Traditional stabilizers have undergone extensive investigation, and the mechanisms by which they act are well understood. This paper presents findings of the effect of sugarcane vinasse wastewater (VI) and sodium alginate (SA) polymer on the compressibility behavior, and microstructural evolution of clay soil using mixing method. The premise of this paper is to eliminate waste material from nature and compare the performance of this material against the use of polymers that have recently been used in improvement. The additives were dissolved in water and then introduced to the dried stratified soil to produce improved soil samples using the mixing technique. Transported unconfined compressive strength (UCS) was examined for 1, 14, and 28 days of treatments with additive ranges of 3–15% for VI and 0.25–1.25% for SA. In clay with high plasticity, the findings show that VI significantly influences increasing the UCS. With the addition of 9% vinasse to the soil at the age of 28 days, the UCS has increased by 78.8%. Additionally, the introduction of 1.25% SA to the soil has increased by 261.9% for the 28-day treatment efficiency significantly. Microstructural and chemical examination revealed that the mineralogical and morphological contents of the stabilized soil were influenced due to the pozzolanic reaction. The results showed that waste by-product liquid was able to significantly increase the strength and compressibility of the clay soil. Using a large volume of waste by-product liquid to stabilize soil, the researchers discovered a straightforward application method. [ABSTRACT FROM AUTHOR]

Rainfall-triggered landslides pose a significant threat to both infrastructure and human lives, making it crucial to comprehend the factors that contribute to their occurrence. Specifically, understanding the relationship between these factors and the amount of rain that is necessary for triggering such events is essential for effective prediction and mitigation strategies. To address this issue, our study proposes a statistical modelling approach using machine learning, specifically the Random Forest algorithm, to investigate the connection between landslide predisposing factors and the daily rainfall intensity threshold necessary for the initiation of shallow landslides in Portugal. By leveraging a comprehensive dataset comprising historical landslide events, associated critical rainfall, and ten distinct landslide predisposing factors, we developed several models and used cross-validation technique to evaluate their performance. Our findings demonstrate that the Random Forest model effectively captures a relationship among landslide predisposing factors, critical daily rainfall intensity, and landslide occurrences. The models exhibit a satisfactory accuracy in assessing the spatial variation of critical daily rainfall intensity based on the predisposing factors, with a mean absolute percentage error (MAPE) of around 17%. Furthermore, the models provide valuable insights into the relative importance of various predisposing factors in landslide triggering, highlighting the significance of each factor. It was found that it takes higher rainfall intensity to trigger shallow landslides in the north region of Portugal when considering critical rainfall events of 3 and 13 days. Slope aspect, slope angle, and clay content in the soil are among the main predisposing factors used for defining the spatial variation of the daily rainfall intensity threshold. [ABSTRACT FROM AUTHOR]

Rapid urbanization has caused numerous construction solid waste landfills. Few studies have explored the impact of multi-source waste soils with remarkable spatial variability on the reliability of landfills. This study aims to characterize the site-specific spatial variability of stockpiled waste soils and perform a probabilistic stability assessment of a real-world landfill slope. An integrated probabilistic landfill analysis framework is developed, consisting of spatial variability characterization, random field modeling, and probabilistic slope stability analysis. Seventy-four groups of clayey waste soil parameters were obtained from a landfill in Hangzhou, China. The artificial mixing behavior makes the shear strengths of waste soils have high variability (coefficients of variation close to 0.5), a high positive cross-correlation (about 0.9), and bimodal marginal probability distributions. The spatial variabilities of the cohesion and friction angle of clayey waste soils are similar, with vertical and horizontal scales of fluctuation being 3.23 m and 34.32 m, respectively. The conditional random field modeling of clayey waste soils provides a more realistic slope stability assessment of the landfill and its impact on the failure probability highly relies on the strength and location of boreholes. More slope reinforcement measures should be adopted for safety management of the next stage of landfilling. [ABSTRACT FROM AUTHOR]

Soil mineralogy and texture are directly related to soil carbon due to the physical properties of the clay surface. Traditional techniques for quantifying carbon in soil are time-consuming and expensive, making large-scale quantification for mapping unfeasible. The alternative is the use of soil sensors, such as diffuse reflectance spectroscopy (DRS), an economical, fast, and accurate technique for predicting carbon stocks. In this sense, this study aimed to (a) investigate the relationship of C with different soil mineralogical, chemical, and physical attributes for different geological and geomorphological compartments; (b) understand which spectral bands are most important for estimating C content; (c) estimate C content from diffuse reflectance spectroscopy using different mathematical techniques and indicate which one is the best for tropical soil conditions; and (d) map C contents in detail. The study area was the Western Plateau of São Paulo (WPSP), which covers approximately 13 million hectares (~ 48% of the State of São Paulo, Brazil). A total of 265 samples were collected in this area. The attributes clay, silt, sand, crystalline and non-crystalline iron, base saturation, soil density, total pore volume, total C, C stock, kaolinite/(kaolinite + gibbsite) and hematite/(hematite + goethite), hematite and goethite contents, and spectral curves were evaluated. The spectra were recorded at 0.5-nm intervals, with an integration time of 2.43 nm s−1 over the 350 to 2500-nm range (350–800 nm—visible—VIS and 801–2500 nm—near-infrared—NIR). The data were subjected to descriptive statistics, Spearman correlation, stepwise analysis, and cluster grouping for characterization purposes; partial least squares regression (PLSR) and random forest (RF) for estimation purposes; and geostatistics analysis for creation of spatial maps. Our results indicate that the highest C contents are associated with more clayey soils, oxidic mineralogy, higher total pore volume, and lower soil density in highly dissected basalt compartments. The random forest algorithm associated with the Vis–NIR spectral range is more efficient for estimating and mapping C contents. This suggests that integrating diffuse reflectance spectroscopy with machine learning techniques holds promise for shaping public policies related to land use, mitigating CO2 emissions, and facilitating the implementation of carbon credit policies in a rapid and economically efficient manner. [ABSTRACT FROM AUTHOR]

Soil degradation, marked by declining organic matter, threatens global food security. The impact of brewer's spent yeast (BSY) on clay and sand was analysed at varying application rates to assess its effectiveness in improving soil quality. A randomized complete block design with three replicates was employed. One kilogram of soil were mixed with BSY at application rates of 2 t/ha and 5 t/ha. The samples were incubated at 26 °C for 5 months with daily watering. We analysed pH, total nitrogen, organic carbon, total phosphorus, and electrical conductivity (EC); microbial activity (total heterotrophic bacteria, actinobacteria, and fungi) and soil enzyme activity (dehydrogenase, catalase, protease). BSY application improved soil quality, particularly in clay. Clay showed increased in pH, EC, N and C. BSY significantly boosted microbial populations (bacteria, fungi) in clay with a lesser effect in sand. Enzyme activity and a fertility index also improved in BSY-treated clay, while sand displayed increased activity of a different enzyme. Results suggest BSY holds promise as an organic fertilizer, especially for clay soils. Further research is needed to optimize application, understand long-term effects, and evaluate economic feasibility and social acceptance. This study contributes to the search for sustainable, local solutions to improve soil health and agricultural practices. [ABSTRACT FROM AUTHOR]

Although many commercial stabilizers are available for the treatment of poor soils; agricultural, agro-industrial, and environmentally friendly stabilizers are always encouraged. In this study, an attempt has been made to assess the effects of brewery spent grain ash (BSGA) on lime-treated clay for stabilization of an expansive clay to be used as road construction material. Brewery spent grain (BSG) is an agro-industrial solid waste product obtained during the brewing of beer. Through burning in an open cylinder, it is converted to BSGA. The clay was subjected to preliminary tests to classify and identify some required engineering properties of the sample. Initially, samples were thoroughly mixed with lime by weight of clay to determine the optimum amount of lime needed throughout the experiments. Through laboratory execution trials, 10% lime was determined to be the optimal amount. Following, BSGA was added to the treated clay, which was previously treated with 10% lime, at various percentages of 2, 4, 6, 8, and 10% BSGA by weight of clay. At 0% BSGA, the unsoaked and soaked California bearing ratio (CBR) rose from 13.56 and 8.24% to their greatest values of 14.99% and 9.3%, respectively, at 6% BSGA. Unconfined compressive strength (UCS) values rose from 112.63 kN/m2 at 0% BSGA to 130.31 kN/m2 at 6% BSGA, which is the highest value. Therefore, it was discovered that BSGA can be a beneficial addition to lime stabilization in clay soil. [ABSTRACT FROM AUTHOR]

Intensified drought exacerbated by climate change aggravates the development of soil desiccation cracking, triggering several weakening mechanisms in surface soils and eventually causing various geohazards and environmental problems. This study investigates the effect and mechanisms of a bio-mediated approach based on microbially induced calcite precipitation (MICP) for remediation of desiccation cracks in soils with different layer thicknesses. We conducted 5 MICP treatment cycles on clayey soil samples to explore the influence of layer thickness on the water evaporation properties, desiccation cracking behaviors, and calcium carbonate content and distribution of MICP-treated soils. The results show that the MICP treatment can significantly decrease the water evaporation rate, the surface crack ratio, average crack width, and total crack length of all soil samples. The crack reduction ratio reaches over 90% after 5 MICP treatment cycles. The soil layer thickness has an obvious influence on the effectiveness of MICP for the clayey soil treatment. Thicker soil samples exhibit wider desiccation cracks, which, in turn, require more MICP treatment cycles for remediation. The calcium carbonate content and distribution of MICP-treated soils is governed by the original desiccation cracks, the wider cracks in thicker soil samples result in the higher calcium carbonate content of soil nearby the cracks, and the denser cracks in thinner soil samples lead to the more homogenous distribution of calcium carbonate. The remediation of soil desiccation cracks is mainly attributed to the coupling effect of the soil volume change and the accumulation of calcium carbonate crystal during MICP treatment. The findings of this study provide new insights into the mechanisms of the interaction between MICP-treated soil and drought climate and contribute to developing environmentally friendly approaches for soil improvement in regions subjected to droughts. [ABSTRACT FROM AUTHOR]

Background and aims: The accumulation of soil organic carbon (SOC) is a crucial process in mitigating climate change and ensuring soil quality. Subtropical plantations in China have shown high potential for enhancing SOC sequestration due to their high carbon sink capacity. However, the dynamics and compositions of SOC after long term afforestation are still poorly understood. Methods: We examined the dynamics of SOC and its fractions of different soil layers (0–5 cm, 5–10 cm, 10–20 cm, 20–40 cm, 40–80 cm, 80–100 cm) in a mixed broadleaf-conifer plantation (BCP), a Masson pine plantation (MP), and a Slash pine plantation (SP), and an enclosed forest (EF) in subtropical China. Both physical fractions (particulate organic carbon (POC), soil clay organic carbon (SOCclay), soil silt organic carbon (SOCsilt)) and chemical fractions (iron-aluminum-bound organic carbon (Fe/Al-OC), and calcium-bound organic carbon (Ca-OC)) were determined. Additionally, soil physicochemical properties were further analyzed. Results: Our results showed the SOC storage in the EF, BCP, MP, and SP in 2019 increased by 82%, 238%, 126%, and 103% respectively compared to 1984. The proportions of MAOC to SOC were respectively as follows: SP (65.9%) > BCP (64.9%) > EF (61.6%) > MP (53.9%). The mean proportions of SOCclay to MAOC were as follows: BCP (71.1%) > EF (66.9%) > MP (58.5%) > SP (51.0%). The mean proportions of Fe/Al-OC to MAOC were as follows: EF (53.3%) > SP (48.3%) > MP (47.9%) > BCP (39.8%). All these proportion increased with soil depth. RDA and PLS-SEM analysis revealed that soil nitrogen content and electrochemical properties (pH and EC) were the main factors that controlled SOC content and fractions. Conclusions: Subtropical plantations have significant soil carbon sequestration capabilities, but they are currently nearing saturation. Soil nitrogen content may be key factor limiting further enhancement of carbon sequestration. Due to the high proportion of MAOC and relative consistent SOC storage, BCP and SP are recommended as priorities for plantation regeneration in subtropical China. [ABSTRACT FROM AUTHOR]

Aims: Climate warming can potentially cause more plant-derived organic substrates into the surface soil. The newly produced carbon may accelerate or restrict native soil organic carbon (SOC) decomposition by priming effects (PE), so as to increase the uncertainty of the feedback prediction between climate change and soil carbon pool. However, it is controversial about the direction and driving factors of the PE of surface SOC in the warming world. Methods: In this meta-analysis, we investigated 1680 pairwise PE determined by 13C or 14C isotope labeling method in surface soils across cropland, grassland and forest from 39 warming experiments to generalize the direction and influencing factors of the warming effects on PE. Results: The meta-analysis showed that warming decreased PE across different ecosystems. The decrease was much greater in forest (effect size: -6.2) than in cropland (effect size: -2.6) and grassland (effect size: -1.7) and was more severe in simple substrates (effect size: -12.1), i.e., small molecules such as glucose and amino acid than that in complex substrates (effect size: -1.7), including plant tissues, residues and pyrolysis products, etc. The effect size of warming on PE was positively correlated with soil clay and pH, while negatively correlated with SOC content, total nitrogen, soil C/N ratio and warming intensity. Conclusions: These findings emphasize that warming will decrease the primed surface SOC loss, particularly in forest or organic matter-rich soils and larger warming intensity. [ABSTRACT FROM AUTHOR]

The degree of salinity, the freezing point, and the amount of unfrozen water are key factors in predicting the temperature, humidity, and mechanical behavior of saline permafrost soils used in construction as foundations for buildings. The results of the experimental studies are presented and a method for calculation of the amount of unfrozen water in saline soils is proposed. The calculated and experimental data show good convergence for both sandy and clay soils of different salinity and water content. [ABSTRACT FROM AUTHOR]

This paper presents a new finite element method (FEM) model to simulate the thermo-hydro-mechanical (THM) responses of water-saturated clay soils. The model can account for the effects of temperature variation on bound water dehydration and the corresponding thermo-poromechanical strains. The governing equations, including mass balance, momentum balance, and energy balance, are derived based on the principles of continuum mechanics for porous media. The impact of bound water dehydration on THM behavior is incorporated into the coupled THM equations. The model is equipped with an unconventional plasticity for more accurate description of elastoplastic behavior. To solve the nonlinear system of equations, a modified Newton–Raphson method is employed. The model is validated using laboratory tests on various clay soils with different geological origins, and reasonable agreement is achieved. The thermally induced contraction behavior of clay soils at a low overconsolidation ratio and thermally induced expansion behavior at a high overconsolidation ratio are well simulated. During heating, the effect of bound water dehydration on the generation of excess pore pressure in clay soils is highlighted in our numerical results. [ABSTRACT FROM AUTHOR]

Background and aims: The frequent occurrence of extreme rainfall events results in soils experiencing drying–rewetting (DRW) cycles. Such rewetting can lead to a surge in soil CO2 emissions; however, the main regulatory factors involved in this priming effect are unclear. Methods: In this study, we conducted a meta-analysis using data extracted from 43 published papers, to determine the direct regulatory factors involved in the priming effect of soil CO2. Results: The results indicated that the priming effect of rewetting on soil CO2 emissions was influenced by ecosystem type, soil properties, climatic factors, and the number of DRW cycles. The priming effect was the highest in cropland but the lowest in grassland when taking flux values observed before rewetting as the control group. It was also greater in acidic soils (pH < 6.5) and soils with a high clay fraction (clay ≥ 30%) than in other soils. The effect size (lnRR) of soil CO2 emissions was exponentially related to the mean annual precipitation (MAP), and decreased with increases in MAP. In DRW experiments, the priming effect of the first rewetting on soil CO2 emissions was the largest, an effect that gradually decreased with the number of DRW cycles, before disappearing completely. Most importantly, soil moisture influenced the peak time and the pulse time of the priming effect: the greater the change in soil moisture, the longer the peak time duration; the higher the maximum soil moisture content after rewetting, the longer the pulse time duration; and the lower the initial soil moisture content, the bigger the priming effect. Conclusion: Generally, physical mechanisms, especially soil moisture, directly regulate the CO2 priming effect during DRW cycles. Thus, this study provides a theoretical basis for assessing and predicting the impact of future precipitation changes on soil carbon cycling. Future studies should also carefully monitor any changes in soil microorganisms in response to changes in soil moisture during DRW cycles, because these appear to be significantly involved in CO2 release from soils. [ABSTRACT FROM AUTHOR]

Some soil characteristics, such as the shear wave velocity, the shear modulus, the Poisson ratio, and the porosity, affect how clay soils behave. The soil design parameters under loading, such as soil liquefaction induced by dynamic earthquake loading, employ the shear wave velocity and shear module with modest stress. In order to understand the pore saturation, the Poisson ratio and seismic velocity ratio are also utilized. Additionally, one of the most crucial physical characteristics for assessing permeability at the base of any engineering structure, resolving consolidation issues that may arise at the foundation of an engineering structure, and influencing the deformation behavior of soils is soil porosity. Predicting the porosity of clay soils is a crucial first step in tackling engineering and environmental issues that may arise in the soil after an earthquake or not. With the use of dynamic soil metrics such as seismic velocities, shear modules, bulk modules, seismic velocity ratios, and Poisson ratios, the current work aims to estimate soil porosity. Seismic refraction was used by various studies in the past to conduct in-situ geophysical research. The lithological characteristics of the soil (such as the grain size, shape, type, compaction, consolidation, and cementation of the grains) and the physical characteristics of the soil (such as porosity, permeability, density, anisotropy, saturation level, liquid–solid transition, pressure, and temperature), as well as the elasticity characteristics of the soil (such as shear modulus (G), bulk modulus (K), Young modulus (E), Poisson ratio (μ) and Lamé constants (λ )) all have an impact on seismic waves passing through a medium. [ABSTRACT FROM AUTHOR]

This investigation examines the effect of clamshell ash (CSA) and lime additives on the physico-mechanical characteristics of kaolinite clay soil stabilized at the optimum silica fume content. Laboratory tests were performed to assess plasticity, shrink-swell characteristics, compaction characteristics, unconfined compressive strength (UCS), shear strength characteristics, mineralogical and morphological microstructure characteristics of stabilized soil specimens. The kaolinite clay soil was stabilized at its optimum silica fume content (6%) to produce the highest strength and was altered with three non-identical proportions of clamshell ash and lime (3%-9%). Cylindrical soil specimens, 76 mm in height and 38 mm in diameter, were moulded and treated for curing periods of 1, 7, 14, and 30 days to examine the strength of the altered soil. The findings revealed that, adding clamshell ash and lime significantly alters the plasticity, shrink-swell, maximum dry unit weights, and optimum moisture contents of the silica fume-stabilized soil. In terms of strength, the beneficial effects of CSA and lime additives were found to be more significant with more extended curing periods. Incremental increases in curing periods resulted in further enhancements in UCS, cohesion, and internal friction angle, indicating continued strength development over time. Microstructural analysis using field emission scanning electron microscopy and X-ray diffraction provided insights into the interparticle bonding mechanisms and microstructural changes induced by the addition of CSA and lime. The emergence of cementitious phases and pozzolanic responses between soil particles and stabilizers contributed to the densification and strengthening of the stabilized soil matrix. The findings of this study provide valuable insights into the potential of clamshell ash and lime additives to enhance the engineering properties of kaolinite clay soil stabilized with silica fume. These results have implications for sustainable soil stabilization practices, offering a promising approach to improve the performance of soils for various engineering applications, including construction and geotechnical projects. [ABSTRACT FROM AUTHOR]

We have studied soils of the western coast of the Chivyrkui and Barguzin bays on the Svyatoi Nos Peninsula, which is the largest peninsula of Lake Baikal in the Republic of Buryatia. Morphogenetic characteristics of soils on the main types of coasts of the peninsula—low abrasion with isolated lagoons, low abrasion, accumulative, and ingression—are given. Rocks in the basis of the coasts of the bays are an important factor of soil formation. It is shown that the genesis of soils depends on the distance from the lake and the altitude, resulting in the difference in their structure and properties. The soils are not directly affected and flooded by lake water due to high mountainous coasts, which are often rocky with steep slopes. Soil formation beyond the floodplain regime is also typical for soils of the closest to the lake level: soddy podzols, which occupy low shores of accumulative types. The particle-size composition of the studied soils varies widely from loose sand to light clay. The common properties of soils include acid and weakly acid reaction, the regressive-accumulative type of humus distribution, and differentiation of bulk oxides along the profile. The revealed evidences of podzolization in Al–Fe-humus soils and of clay accumulation in brown soils are related to sufficient moistening of the coasts and the warming effect of the lake water mass. The research results may be used in landscape planning in territorial organization and monitoring work in recreation areas. [ABSTRACT FROM AUTHOR]

Granite residual soil is a widely encountered clayey soil with unique microscopic soil structures. Its soil structures mainly stem from the presence of interparticle cementation by iron oxide. An attempt is made herein to experimentally quantify the impact of interparticle iron oxide cementation on soil's mechanical properties, particularly in the high suction range. The amount of interparticle cementation is artificially generated by mixing soil samples with varying mass fractions of iron hydroxide colloid. The mechanical behavior of these soil samples in the full suction range is measured via the drying cake test. Preliminary experimental results demonstrate that interparticle iron oxide cementation can significantly decrease soil shrinkage (by up to 52%), and substantially increase soil elastic modulus (by up to 1.83 times) and negative suction stress change (by up to 0.82 times). [ABSTRACT FROM AUTHOR]

In this investigation, the structural strength of a clayey soil compacted at three different dry densities (1.7, 1.6 and 1.5 Mg/m3) and three different compaction water contents (20%, 16% and 12%) was studied by using a micropenetrometer. The penetration curves at various water contents during the drying and wetting cycle were analyzed. The maximum unit penetration strength and the penetration stiffness were used to represent the structural strength. Experimental results show that the structural strength increases with decreasing water content. At a given water content, the larger dry density, the larger structural strength and the smaller hysteresis loop induced by the drying-wetting cycle. At a higher dry density, the structural strength increases and the drying-wetting cycle induced hysteresis loop becomes smaller. Specimens compacted on the wet side of optimum water content exhibit a dispersed structure and those compacted on dry side of optimum water content have an aggregated structure. For soils with a dispersed structure, the structural strength increases with decreasing water content and the growth rate is gradually accelerated. However, for soils with an aggregated structure, when dried to water content lower than 8%, the structural strength increases by a small degree or even decreases. Moreover, the hysteresis loop of the soil specimens with dispersed structure is much smaller than those with an aggregated structure. [ABSTRACT FROM AUTHOR]

There are three main electrochemical factors affecting the electroosmotic flow in clay soil: the voltage loss at the clay/electrode interface, the type of current carriers in the soil, and the ion composition change in the clay due to voltage application. Appropriate evaluation of these factors is important to cost effectively implement electroosmosis for in situ soil consolidation projects. In this study, three different experimental systems were developed and used to investigate electrochemical reactions occurring in reconstituted and natural marine clay during electroosmotic consolidation. The results of polarization tests show that the voltage loss at the clay/electrode interface is different depending on the combination of the clay material and electrode material. The results of electroosmotic element test also show that electroosmotic dehydration does not increase if large current–voltage value is applied and that an optimal current–voltage value for causing electroosmosis depends on the cohesive soil composition. If the clay contains a lot of oxidizable ions, such as sodium, these ions affect electrophoresis and chemical reactions that occur in the soil. Therefore, the optimal configuration to apply electric current also differs depending on the clay. The results of laboratory-scale electroosmotic dehydration tests, arranged in a realistic in situ layout, are performed to study the relationship between soil dehydration, consolidation, and surface crack generation. [ABSTRACT FROM AUTHOR]

Information on microbial biomass carbon (MBC) is crucial to assess their stocks and role for plant nutrient release in soil. Next to fumigation-extraction, molecular methods are routinely used to estimate the contribution of fungi, bacteria, and archaea to the soil microbial community. However, more information on the links between these different indices would deepen the understanding of microbial processes. The current study is based on 11 datasets, which contain MBC and MBN data obtained by fumigation-extraction and information on bacterial, archaeal, and fungal gene abundance, totalling 765 data points from agricultural, forest, and rangeland soils. Some of these datasets additionally provide information on double-stranded deoxyribonucleic acid (dsDNA) and fungal ergosterol. MBC varied around the median of 206 µg g−1 soil. MBN followed with a median MB-C/N ratio of 4.1. Median microbial gene abundance declined from bacteria (96 × 108) to archaea (4.4 × 108) to fungi (1.8 × 108). The median ratio of MBC/dsDNA was 15.8 and that of bacteria/dsDNA was 5.8 × 108 µg−1. The relationships between MBC and dsDNA as well as between bacterial gene abundance and dsDNA were both negatively affected by soil pH and positively by clay content. The median ergosterol/MBC and fungi/ergosterol ratios were 0.20% and 4.7 (n × 108 µg−1), respectively. The relationship between fungal gene abundance and ergosterol was negatively affected by soil pH and clay content. Our study suggests that combining fumigation-extraction with molecular tools allows more precise insights on the physiological interactions of soil microorganisms with their surrounding environment. [ABSTRACT FROM AUTHOR]

Evaluating the liquefaction capacity of saturated loose sandy and clayey soils is an important task to be completed in the course of implementing new construction projects in seismic areas. This article addresses the main characteristics and input parameters of three soil models, including HS small, UBC3D-PLM, and PM4Silt. The behavior of the "soil base–pile foundation–structure" system is examined by using these models to simulate the soil behavior during an earthquake. The results demonstrate the main differences between these models and draw attention to the importance of the choice of a soil model for seismic analysis, particularly when soil liquefaction is considered. [ABSTRACT FROM AUTHOR]

Laboratory experiments on clayey soils under dynamic triaxial compression were conducted to establish a nonlinear relationship between the dynamic modulus of soil deformation and the frequency of impact. The most significant increase in the dynamic modulus of soil deformation is observed under an increase in frequency from 5 to 10 Hz. In comparison with fluvioglacial soils, the dynamic deformation modulus in glacial loams grows slower under an increase in frequency. This confirms the dependence of the obtained relations on the genesis of soils. The research results were used to develop vibration protection systems for high-precision equipment in high-tech industries. [ABSTRACT FROM AUTHOR]

Coir is a promising natural fiber that can be used for soil stabilization through fiber reinforcement. In this paper, weight gain, reduction in water absorption, and single-fiber tensile strength tests are performed to evaluate the application of different natural agents such as neem oil, kerosene, and cashew nutshell liquid (CNSL) in improving the mechanical properties and durability of coir fibers. Tri-axial tests are performed on soil specimens cured for 3, 28, and 180 days to determine the improvement in their shear strength when reinforced with coir fibers treated with different agents. The fiber reinforcement led to an increase in the shear strength of the soil by improving cohesion and friction angle. Among the different agents used, the CNSL is found to be the most effective agent for coir fiber treatment. [ABSTRACT FROM AUTHOR]

In this study, fast-growing poplar reclaimed from abandoned homestead in Xixian New District, Xi'an City, Shaanxi Province, was used as the research object to explore the multi-fractal characteristics of soil particle size distribution under different management modes of abandoned land (control), irrigation, fertilizer irrigation and mixed fertilizer irrigation. The results showed that the mean values of soil clay, silt and sand in abandoned land were 14.58%, 81.21% and 4.22% respectively, 14.08%, 79.92% and 5.99% under irrigation, 15.17%, 81.19% and 3.64% under fertilizer irrigation, and 16.75%, 80.20% and 3.05% in mixed fertilizer treatment. From 40 cm, with increasing soil depth, soil clay particles increase under irrigation, fertilizer irrigation, and mixed fertilizer irrigation modes. The single fractal dimension of soil particle size distribution (D) in each treatment ranges from 2.721 to 2.808. At 60–100 cm, D shows fertilizer irrigation > mixed fertilizer irrigation > irrigation > abandoned land, indicating that fertilization and irrigation can increase the fine-grained matter of deep soil particles and reduce soil roughness. Compared with abandoned land, under irrigation, fertilizer irrigation and mixed fertilizer modes the capacity dimension (D0), entropy dimension (D1), correlation dimension(D2), shape characteristics of the multifractal spectrum (Δf) and overall inhomogeneity of the soil particle size distribution (D0–D10) indicate an uneven distribution of soil particle size; fractal structure characteristics of soil (D−10–D0) indicate a simplified soil structure, and degree of dispersion of soil particle size distribution (D1/D0) indicates that soil particle size is distributed in dense areas. Pearson correlation analysis showed that D was significantly correlated with clay, sand, D0–D10, soil organic matter (SOM) and soil available phosphorus (SAP) (P < 0.05). Stepwise regression analysis showed that clay was the main controlling factor of D and D0–D10 changes. The research results can provide some potential indicators for the quality evaluation of abandoned homestead reclamation. [ABSTRACT FROM AUTHOR]

Understanding the efficacy of alternative phosphorus (P) sources in tropical soils is crucial for sustainable farming, addressing resource constraints, mitigating environmental impact, improving crop productivity, and optimizing soil-specific solutions. While the topic holds great importance, current literature falls short in providing thorough, region-specific studies on the effectiveness of alternative P sources in Brazilian tropical soils for maize cultivation. Our aim was to assess the agronomic efficiency of alternative P sources concerning maize crop (Zea mays L.) attributes, including height, shoot dry weight, stem diameter, and nutrient accumulation, across five Brazilian tropical soils. In greenhouse conditions, we carried out a randomized complete block design, investigating two factors (soil type and P sources), evaluating five tropical soils with varying clay contents and three alternative sources of P, as well as a commercial source and a control group. We evaluated maize crop attributes such as height, dry weight biomass, and nutrient accumulation, P availability and agronomic efficiency. Our results showed that, although triple superphosphate (TSP) exhibited greater values than alternative P sources (precipitated phosphorus 1, precipitated phosphorus 2 and reactive phosphate) for maize crop attributes (e.g., height, stem diameter, shoot dry weight and phosphorus, nitrogen, sulfur, calcium and magnesium accumulation). For instance, PP1 source increased nutrient accumulation for phosphorus (P), nitrogen (N), and sulfur (S) by 37.05% and 75.98% (P), 34.39% and 72.07% (N), and 41.94% and 72.69% (S) in comparison to PP2 and RP, respectively. Additionally, PP1 substantially increased P availability in soils with high clay contents 15 days after planting (DAP), showing increases of 61.90%, 99.04%, and 38.09% greater than PP2, RP, and TSP. For Ca and Mg accumulation, the highest values were found in the COxisol2 soil when PP2 was applied, Ca = 44.31% and 69.48%; and Mg = 46.23 and 75.79%, greater than PP1 and RP, respectively. Finally, the highest values for relative agronomic efficiency were observed in COxisol2 when PP1 was applied. The precipitated phosphate sources (PP1 and PP2) exhibited a similar behavior to that of the commercial source (TSP), suggesting their potential use to reduce reliance on TSP fertilization, especially in soils with low clay contents. This study emphasized strategies for soil P management, aimed at assisting farmers in enhancing maize crop productivity while simultaneously addressing the effectiveness of alternative P sources of reduced costs. [ABSTRACT FROM AUTHOR]

Identifying strength parameters under drained conditions is crucial for monitoring and evaluating long-term soil deformations caused by structures built on or in soils. Geotechnical engineers carry out direct shear tests (DSTs) and triaxial tests (TAs) in the laboratory to identify strength parameters under such conditions. However, it can take considerable time to ascertain the failure envelope of even a single soil in the TA tests commonly used to evaluate drained conditions. This study explores whether the effective internal friction angle (ϕ′)—as one of the drained shear strength parameters of remolded soils—can be identified with a vane shear test (VST) at very low (down to 0.001/min) rotation speeds, which is easy to implement and takes a relatively shorter time. For this aim, 18 different remolded soil samples with a wide range of plasticity were prepared using static compaction in the laboratory. DST tests were conducted under drained conditions to evaluate the drained shear strengths of the remolded soil samples. VST results indicate that the peak shear strength decreases with the rotation speed as expected. Shear strengths obtained from the slowest VSTs were correlated with ϕ′s from DSTs. While the results were not encouraging, it was observed that the results of VSTs still could be used in a predictive equation for ϕ′ which, as a function of LL and total density as well as VST strength parameter, the regression coefficient rose to 0.92. Some effective cohesion intercepts were observed during DSTs, which in turn somewhat reduce the predicted ϕ′s. [ABSTRACT FROM AUTHOR]

Low-volume roads are anticipated to have less traffic and provide access to socio-economic activities in rural areas. The present study deals with the stabilisation of soil with locally available waste materials, i.e. low calcium fly ash (FA) and brick dust (BD). These two wastes are available abundantly and lead to an increase in pollution levels. Initially, lime was added to make the silty clayey soils plastic-free. The initial consumption of lime was found to be 5%. Then, the soil was stabilised with cement fly ash and cement brick dust techniques for strength, durability and shrinkage evaluation. The cement was varied from 2 to 8% with FA and BD by fixing the ratio to 1:3 as per AASHTO guidelines. The unconfined compressive strength (UCS), indirect tensile strength test and California bearing ratio were conducted for strength evaluation. The wetting and drying cycles were evaluated for durability analysis. The linear shrinkage cracking was evaluated after the curing period of 28 days. It was observed that there was a magnificent increase in strength and durability values. The maximum UCS attained value was so high that it could act as a replacement for the granular sub-base layer in the pavement structure. The linear shrinkage evaluated at fixed relative humidity was significantly reduced. The statistical analysis reported that there was a significant difference between the two admixtures. The utilisation of these wastes not only enhances strength, but also deficits the cost of construction along with reducing the pollutants in the environment. [ABSTRACT FROM AUTHOR]

Electrokinetics has gained importance as a sustainable soil modification and remediation method for improving problematic sites. The formation of cracks during the electrokinetic treatment is an important concern during the field implementation of the process. Therefore, considering this, this study investigated the impact of a voltage gradient on the performance evaluation of electrokinetic consolidation clayey soil after adding a lime. The performance was evaluated regarding cumulative discharge, surface settlement, power consumption, reducing water content, alteration in soil pH, and crack formation. The surface settlement increases by 50% for the applied voltage gradient of 1.00 V/cm compared to that of 0.25 V/cm. The power consumption in the case of 1.00 V/cm after the addition of lime is 3.67 times compared to that without lime; however, the difference is insignificant for 0.50 V/cm. Further, the pH near the cathode increases to 10.94 from 7.81 after the addition of lime in the case of 0.50 V/cm. Finally, adding lime helps drastically reduce the surface crack formed during the electrokinetic treatment. [ABSTRACT FROM AUTHOR]

With the widespread use of geopolymer, the effective activation and utilization of thermally activated termite soils as alternative or eco-friendly material are great of interest. The present study investigated the use of calcined termite soils (TC) in geopolymer pastes and mortars as a precursor, while metakaolin (MK) was used as a reference material to prepare control samples. The physicochemical properties of both raw and calcined solid precursors as well as geopolymer pastes and mortars were characterized using various techniques, including BET, PSD, XRF, XRD, setting time, ICC, and SEM/EDS. Results showed that termite soil can be successfully employed as a starting material in geopolymer production. Pastes and mortars prepared using TC gave significant compressive strengths of 43.2 and 33.2 MPa, respectively, although they were approximately 26% and 6% lower than control samples made using MK. Based on the analytical studies, better mechanical performance of MK-based binders compared to TC-based ones is attributed to the presence of reactive phases within MK that promotes the geopolymerization resulting in the development of a stronger geopolymer network and better connectivity within the matrix. It can be concluded that TC can be considered as a suitable raw material for the production of geopolymer binder considering the availability and accessibility in certain regions. [ABSTRACT FROM AUTHOR]

Understanding the response of salt marshes to flooding is crucial to foresee the fate of these fragile ecosystems, requiring an upscaling approach. In this study we related plant species and community response to multispectral indices aiming at parsing the power of remote sensing to detect the environmental stress due to flooding in lagoon salt marshes. We studied the response of Salicornia fruticosa (L.) L. and associated plant community along a flooding and soil texture gradient in nine lagoon salt marshes in northern Italy. We considered community (i.e., species richness, dry biomass, plant height, dry matter content) and individual traits (i.e., annual growth, pigments, and secondary metabolites) to analyze the effect of flooding depth and its interplay with soil properties. We also carried out a drone multispectral survey, to obtain remote sensing-derived vegetation indices for the upscaling of plant responses to flooding. Plant diversity, biomass and growth all declined as inundation depth increased. The increase of soil clay content exacerbated flooding stress shaping S. fruticosa growth and physiological responses. Multispectral indices were negatively related with flooding depth. We found key species traits rather than other community traits to better explain the variance of multispectral indices. In particular stem length and pigment content (i.e., betacyanin, carotenoids) were more effective than other community traits to predict the spectral indices in an upscaling perspective of salt marsh response to flooding. We proved multispectral indices to potentially capture plant growth and plant eco-physiological responses to flooding at the large scale. These results represent a first fundamental step to establish long term spatial monitoring of marsh acclimation to sea level rise with remote sensing. We further stressed the importance to focus on key species traits as mediators of the entire ecosystem changes, in an ecological upscaling perspective. [ABSTRACT FROM AUTHOR]

Pseudostellaria heterophylla of the Caryophyllaceae family is an important medicinal herb in traditional Chinese medicine, but it encounters continuous cropping obstacle during cultivation. This study aimed to study the differences in the response of Pseudostellaria heterophylla cultivation to soil microorganisms and phenolic substances in different types of soil (Loamy soil and Clayey soil). The analysis of soil metabolites using HPLC-ESI-Q/TOF-MS and HPLC-DAD techniques revealed that the content of various phenolic components in the rhizosphere soil increased significantly after Pseudostellaria heterophylla cultivation. Pseudostellaria heterophylla cultivation in yellow soil could increase the abundance of Proteobacteria, Ascomycota, and Thermoplasmatota, while in brown soil, the abundance of Ascomycota significantly decreased. In addition, Pseudostellaria heterophylla cultivation could increase the α-diversity of bacteria and fungi in yellow soil, while reducing the α-diversity of archaea, and the impact on diversity in brown soil was relatively small. Correlation analysis showed that phenolic compounds were more likely to regulate the genera Bradyrhizobium, Calcarisporiella, Boothiomyces and Methanocella. Pseudostellaria heterophylla may regulate rhizosphere microbial diversity and community structure by secreting phenolic. However, in different types of soil environments, the response mechanism of soil microorganisms to Pseudostellaria heterophylla planting might vary. Our study provides new insights that the variability in the response of different soil types to Pseudostelariae heterophylla cultivation should be taken into account when developing strategies for reducing continuous cropping obstacles in medicinal plants. [ABSTRACT FROM AUTHOR]

Aims: We aimed to understand how eucalypt forests planted in highly weathered natural low fertile soils of the Brazilian Cerrado would benefit from the use of limestone (+ L) and phosphogypsum (+ G) applied banded or broadcast and incorporated or non-incorporated. Methods: The treatments applied here can be grouped into three, as follows: Group 1 – consists of three treatments that did not receive any limestone or phosphogypsum (control); Group 2 – consists of four treatments with + L only (different ways of applying + L); and Group 3 – consisting of two treatments including + L + G combined (different ways of applying + L + G). Results: The + L banded (Ba) and incorporated (I) (+ LBaI – Group 2) provided the greatest residual effect on soil chemical characteristics, increasing Ca2+ and Mg2+ availability and decreasing exchangeable and active acidity, regardless of the soil type. Consequently, an increase of 39.4% (~ 91.4 m3 ha−1) and 16.7% (~ 47 m3 ha−1) of eucalypt wood volume was obtained in the sandy and clay soils, respectively, when compared to the controls. However, when + L and + G were combined (Group 3) it increased S-SO42− concentrations, improving root development in the deeper layers. This resulted in the highest eucalypt productions with 58% (122.7 m3 ha−1) and 29% (94.7 m3 ha−1) more wood than the control in the sandy and clay soils, respectively. Conclusions: The application of + L and + G increased wood production of eucalypt planted forests in highly weathered and low fertile tropical soils due to better plant nutrition and soil amelioration. [ABSTRACT FROM AUTHOR]

This study comprehensively investigates the effect of DC voltage gradient (VG) on energy consumption and the removal of ions (total Cr, Na+, Clˉ, and K+) from salt-affected clayey soil. In this work, different VG (i.e., 0.5, 1, and 2 V cm−1) were applied over the artificially contaminated soil for 48 h during electrokinetic experiments to determine the electric potential distribution, electroosmotic flow (EOF), and electric current variation. The results revealed that the VG directly influences the EOF rate and electromigration of ionic species present in the pore solution of the soil samples. The higher removal of ions was achieved with the intensity of applied electric field (EF) due to electromigration and higher EOF rate. Therefore, the maximum ion removal was achieved at 2 V cm−1 [i.e., total Cr (71%), Na+ (91%), Clˉ (64%), and K+ (63%)]. In addition, the EOF rate decreased with increasing treatment time, which was attributed to the progression of acidic-alkaline fronts in soil samples. The collision of acidic-alkaline fronts resulted in a large VG in a narrow soil region of pH jump reducing the EOF and electromigration of ions. Regardless of low EF (i.e., 0.5 V cm−1), the EOF rate and removal of ions decreased [i.e., total Cr (36%), Na+ (58%), Clˉ (45%), and K+ (37%)]. Moreover, the higher EF (i.e., 2 V cm−1) resulted in higher energy consumption (218.6 kWh m−3) and a reduction in the electrical conductivityof soil from 5.2 to 1.29 dS m−1. [ABSTRACT FROM AUTHOR]

The production of biosurfactants and lipases through solid-state fermentation (SSF) processes remains relatively unexplored, especially in bacterial applications. The use of solid matrices, eliminating the need for precipitation and recovery processes, holds significant potential for facilitating bioremediation. This study aimed to simultaneously produce biocompounds via SSF using Bacillus methylotrophicus and employ the fermented substrate for remediating soil contaminated with 20% biodiesel. Initial efforts focused on determining optimal conditions for concurrent lipase and biosurfactant production during an 8-day fermentation period. The selected conditions, including a substrate mix of wheat bran and corn cob (80/20), 75% moisture, 1% glycerol inducer, 2% nitrogen, and 1% sugarcane molasses, resulted in a 24.61% reduction in surface tension and lipase activity of 3.54 ± 1.20 U. Subsequently, a 90-day bioremediation of clayey soil contaminated with biodiesel showcased notable biodegradation, reaching 72.08 ± 0.36% within the initial 60 days. The incorporation of biocompounds, biostimulation, and bioaugmentation (Test E2) contributed to this efficacy. The use of the fermented substrate as a biostimulant and bioaugmentation agent facilitated in situ biocompound production in the soil, leading to a 23.97% reduction in surface tension and lipase production of 1.52 ± 0.19 U. [ABSTRACT FROM AUTHOR]

The technique of mass soil stabilization using alternative binders to Portland cement (PC) has been used successfully in the past. However, knowledge gaps exist regarding the design of these binders. Ground-granulated blast furnace slag (GGBS) has been widely used as a substitute for PC; however, it requires an alkaline activator (e.g. lime and PC) to promote pozzolanic reaction and strength enhancement. A candidate that presents a less energy-intensive manufacturing and carbon footprint is carbide lime (CL), a by-product of acetylene gas production, rich in Ca(OH)2. The main problem with the pozzolanic binder in the stabilization technique is its slow reaction kinetics and the long time required for laboratory-scale investigations before in situ application. Therefore, this research presents a dosing study of a ternary binder (TB) comprising CL, GGBS and PC type III (CEM-III) to mass-stabilize a clayey organic soil using thermal curing as an innovative technique to improve the feasibility of laboratory-scale investigations. The effects of binder composition and thermal curing time on the evolution of strength, stiffness, mineralogy, and microstructure were determined. The results, supported by a statistical analysis (ANOVA) and by a multivariate regression analysis (MRA), have shown that the new TB produced a superior mechanical response to soil samples stabilized exclusively with CEM-III. This was evidenced by a less porous microstructure (more reaction products) and mainly the formation of a C–A–S–H gel, as a product of CEM-III hydration and alkaline activation of GGBS (blended cement), whereby the CL content played a key role for the development of the long-term pozzolanic reaction. [ABSTRACT FROM AUTHOR]

The Mg isotopic compositions of siliciclastic components (δ26Mgsili) of sediments and sedimentary rocks have been commonly used to constrain the intensity of continental weathering, based on observations of, (1) an upward enrichment of 26Mg in modern weathering profiles, (2) preferential uptake of 26Mg in soil clays, and (3) general positive correlations between weathering intensities and δ26Mgsili values. However, not all weathering profiles display an upward increase of δ26Mgsili, and not all soil clays enrich in 26Mg, complicating the interpretations of δ26Mgsili data of sediments and sedimentary rocks. To further explore the controls of δ26Mgsili of sediments and sedimentary rocks, here we measured δ26Mgsili, mineralogical compositions and major element compositions of deep sea sediments from South China Sea (SCS) and carbonate rock samples from two late Paleozoic sections in South China. Carbonate samples show decreasing trends of both normalized Mg concentration (Mgnorm) and δ26Mgsili values with the increase of weathering intensity, while SCS sediments samples do not show any correlation between Mgnorm or δ26Mgsili values and weathering intensity. A three-stages weathering model is developed to explain the observed Mgnorm and δ26Mgsili data. In the new model, weathering can be divided into three stages, (1) the preliminary weathering stage characterized by dissolution of primary minerals and formation of secondary clay minerals in saprolite, (2) the transitional stage with massive vermiculite and chlorite formation on the bottom of soil, and (3) the advanced stage showing dissolution of vermiculite and chlorite in the top of soil. The new model explains an δ26Mgsili increase and Mgnorm decrease with an increase weathering intensity in preliminary weathering stage and decrease of Mgnorm and δ26Mgsiliwith increase weathering intensity in advanced weathering stage. The revised weathering model warrants the application of Mg isotope in the study of continental weathering in deep time. [ABSTRACT FROM AUTHOR]

The present research employs new boosting-based ensemble machine learning models i.e., gradient boosting (GB) and adaptive boosting (AdaBoost) to predict the unconfined compressive strength (UCS) of geopolymer stabilized clayey soil. The GB and AdaBoost models were developed and validated using 270 clayey soil samples stabilized with geopolymer, with ground-granulated blast-furnace slag and fly ash as source materials and sodium hydroxide solution as alkali activator. The database was randomly divided into training (80%) and testing (20%) sets for model development and validation. Several performance metrics, including coefficient of determination (R2), mean absolute error (MAE), root mean square error (RMSE), and mean squared error (MSE), were utilized to assess the accuracy and reliability of the developed models. The statistical results of this research showed that the GB and AdaBoost are reliable models based on the obtained values of R2 (= 0.980, 0.975), MAE (= 0.585, 0.655), RMSE (= 0.969, 1.088), and MSE (= 0.940, 1.185) for the testing dataset, respectively compared to the widely used artificial neural network, random forest, extreme gradient boosting, multivariable regression, and multi-gen genetic programming based models. Furthermore, the sensitivity analysis result shows that ground-granulated blast-furnace slag content was the key parameter affecting the UCS. [ABSTRACT FROM AUTHOR]

The results of the search for and study of the Late Pleistocene soils in the north of Western Siberia are described. The theoretical basis is an ice-free model of the evolution of Pleistocene landscapes in the region, because the alternative model of its glacial cover excludes the preservation of paleosols. Glacial deposits are absent in this region, and paleosol levels are detectable in the sections of high river terraces exposing the Late and Middle Pleistocene sediments. They correspond to the chronointervals with landscape conditions favorable for pedogenesis; namely, soils of the (1) Kazantsevo thermochron (marine isotope-oxygen stage MIS5 overlying the Middle Pleistocene alluvium), (2) Karginsky interstadial (MIS3), and (3) the end of Sartan cryochron (MIS2). The pedogenetic interpretation of these paleosols is based on morphogenetic analysis, including micromorphological examination. According to this analysis, (i) the stage of taiga soil formation with clay illuviation in the polygenetic profile of MIS5 paleosol was replaced by a colder tundra phase with suprapermafrost gleying; (ii) characteristic of the MIS3 paleosols were tundra-steppe conditions, under which gleying and cryogenesis were combined with the neoformation of carbonates; and (iii) the paleosol level of the end of MIS2 was the result of tundra-swamp pedogenesis and included gleyed pedosediments that filled ice-wedge pseudomorphs. The latter fact allows us to identify the Late Sartan Taz–Nadym cryogenic soil horizon. The results are correlated with synchronous stratigraphic schemes for adjacent regions suggesting the construction of the soil–permafrost paleorecord for the north of Western Siberia. This is important, because the interpretation of the modern surface soils requires special approaches in order to take into account relict pedogenic horizons that are often found in their profiles. [ABSTRACT FROM AUTHOR]

Expansive soil, also called swelling soil can cause severe damage to buildings and foundations due to the high swell-shrink behavior corresponding to moisture content changes. Slag, which is defined as the by-product of the iron and steel-making process, has been widely used as a stabilizer agent for developing clay soil mechanical characteristics. This review paper highlighted the findings of previous studies on treating expansive soils utilizing several types of slag. The effect of mixing slag with other additives such as Portland cement and lime on expansive soil swelling properties was reviewed. [ABSTRACT FROM AUTHOR]

Tacca chantrieri André (1901) is a valuable evergreen rhizomatous herbaceous species that plays a crucial ecological and economic role in Vietnam's evergreen broadleaf forests. However, the degradation of forest ecosystems poses a significant threat to its survival in the wild. This study aimed to develop a model for determining the potential land suitable for Tacca chantrieri in Ba-Vi Natural Park, utilizing SoilGrid data. The results revealed that the species primarily thrives in Ba Vi, Minh Quang, and Yen Bai communes, covering approximately 20.92% of the total area. Despite its adaptability, Tacca chantrieri is highly scarce in the wild, with only 30 identified population spots concentrated along streams and slopes. The Jackknife standard analysis identified five key variables influencing the potential distribution of Tacca chantrieri in Ba-Vi National Park: clay composition in soil (36.9% contribution), bulk (22.6%), organic carbon density (OCD) (16.4%), coarse fragments (CF) (13%), and silt (9.3%). These findings highlight the applicability of SoilGrid data in species distribution modeling for small areas, particularly in the absence of site-specific soil data. However, for precise and site-specific information, field data collection remains indispensable. The high AUC values (training data: 93.9%, test data: 94.9%) indicate the feasibility of developing an effective model for evergreen rhizomatous herbaceous species. [ABSTRACT FROM AUTHOR]

Current ware potato yields in the Netherlands are approximately 70% of their potential. It is hypothesised by several stakeholders within the potato value chain that part of the potato yield gap is caused by a lack of phosphorus (P) and potassium (K) application. In this study, we analysed for 46 farmers' fields if increasing P and K fertiliser application rates led to a higher yield and yield quality. We found that, on average, increased P and K fertiliser application did not result in a significantly higher yield for two currently cropped potato cultivars on two different soil types in the Netherlands (Innovator on clay soils and Fontane on sandy soils) and in two years (2019 and 2020). However, on sandy soils at relatively lower farmer K application rates, our K application led to a small positive yield response up to 5 t ha−1. On clay soils, there was an average positive yield response to our K application at lower yield levels of the control. For P, we did not find any correlation between yield response to P application and the amount of P applied by farmers or any of the measured soil parameters. In terms of yield quality, the K application led to a slight reduction in underwater weight on sandy soils in 2019 and a slight increase in the yield of large tubers in 2020. We conclude that, although in some fields there was a small positive yield effect of increased K application, increasing P and K application rates will not narrow the potato yield gap and improve potato yield quality in the Netherlands. Instead, increasing the P and K application will decrease P and K use efficiency and hence is not recommended from an environmental and economic perspective. [ABSTRACT FROM AUTHOR]

Acquiring comprehensive insights into soil properties at various spatial scales is paramount for effective land management, especially within small catchment areas that often serve as vital pastured landscapes. These regions, characterized by the intricate interplay of agroforestry systems and livestock grazing, face a pressing challenge: mitigating soil degradation while optimizing land productivity. This study aimed to analyze the spatial distribution of eight topsoil (0–5 cm) properties (clay, silt, sand, pH, cation exchange capacity, available potassium, total nitrogen, and soil organic matter) in a small grazed catchment. Four machine learning algorithms—Random Forest (RF), Support Vector Machines (SVM), Cubist, and K-Nearest Neighbors (kNN)—were used. The Boruta algorithm was employed to reduce the dimensionality of environmental covariates. The model's accuracy was assessed using the Concordance Correlation Coefficient (CCC) and Root Mean Square Error (RMSE). Additionally, uncertainty in predicted maps was quantified and assessed. The results revealed variations in predictive model performance for soil properties. Specifically, kNN excelled for clay, silt, and sand content, while RF performed well for soil pH, CEC, and TN. Cubist and SVM achieved accuracy in predicting AK and SOM, respectively. Clay, silt, CEC, and TN yielded favourable predictions, closely aligning with observations. Conversely, sand content, soil pH, AK, and SOM predictions were slightly less accurate, highlighting areas for improvement. Boruta algorithm streamlined covariate selection, reducing 23 covariates to 10 for clay and 4 for soil pH and AK prediction, enhancing model efficiency. Our study revealed spatial uncertainty patterns mirroring property distributions, with higher uncertainty in areas with elevated content. Model accuracy varied by confidence levels, performing best at intermediate levels and showing increased uncertainty at extremes. These findings offer insights into model capabilities and guide future research in soil property prediction. In conclusion, these results urge more research in small watersheds for soil and territorial management. [ABSTRACT FROM AUTHOR]

Moisture migration in unsaturated soils is a result of the interaction between temperature and soil microstructure. In order to reveal the mechanism of moisture increase of subgrade soils under diurnal cycle conditions, a series of macro and microscopic tests were carried out on the unsaturated silty clay and sand soil, including liquid–vapor mixed migration tests simulating a one-dimensional subgrade, environmental scanning electron microscope (ESEM), and matrix suction test. Then, the soil microstructure in microscopic images was investigated using the particle (pores) and cracks analysis system (PACS). Next, the relationship between the thermal effects of the soil–water characteristic curve (SWCC) and changes in soil microstructure was analyzed. Finally, the change mechanism of liquid–vapor mixed migration based on the change in soil microstructural under thermal effects was analyzed. The results showed under the diurnal cycle, both the silty clay and sand soil columns appeared in the phenomenon of a "diurnal cycle of water vapor migration", which led to moisture accumulation at the top of the soil layer. In silty clay soil column, moisture was primarily driven by water vapor pressure and migrated upwards. Additionally, moisture redistribution led to changes in soil microstructure, which in turn influenced the process of moisture migration. The moisture content in the upper soil layer increased making both inter-aggregate and intra-aggregate pores decrease. The moisture content in the lower soil later decreased, leading to the water-holding capacity of the lower soil layer to increase. So, the moisture migration gradually decreased at night. In the sand soil column, moisture migration was mainly driven by gravity potential and migrated downwards. Moisture redistribution made inter-aggregate pore and matrix suction of the upper soil layer increase, leading to an increase in moisture migration at night. [ABSTRACT FROM AUTHOR]

Foundation plays a vital role in weight transfer from the superstructure to substructure. However, foundation characteristics such as pile group, piled raft, and footing remain unfolded due to their highly non-linear behaviour in different soil types. Bibliography analysis using VOSvierwer algorithm supported the significance of the research. Hence, this study investigates the load-bearing capacity of different types of foundations, including footings, pile groups, and piled rafts, by analyzing experimental data using finite element tools such as PLAXIS 2D and GEO5. The analysis involves examining the impact of various factors such as the influence of surcharge and the effect of different soil types on the load-bearing capabilities of the different types of foundation. For footing, parametric investigations using PLAXIS 2D are conducted to explore deformational changes. Pile groups are analyzed using GEO5 to assess their factor of safety (FOS.) and settling under various criteria, such as pile length and soil type. The study also provides insight into selecting the right type of foundation for civil engineering practice. Findings showed that different soil types have varying deformational behaviours under high loads with sandy soil having less horizontal deformation than clayey soil. Also, it was observed that increasing the pile thickness by 50% resulted in a reduction of 13.88% in settlement and an improvement of 16.66% in the FOS. In conclusion, this study highlights the importance of professionalism, exceptional talent, and outstanding decision-making when assessing the load-bearing capabilities of various foundation types for building structures. [ABSTRACT FROM AUTHOR]

Clay minerals in soils and rocks exhibit large volume change upon interaction with water and this behavior becomes even more complex when the strata are being stressed by the engineering and environmental loads. Therefore, a realistic prediction of the hydro-mechanical behavior of the clay-bearing strata is always a challenge due to their coupled swelling-mechanical response in the cases of geotechnical and geoenvironmental engineering problems, nuclear waste storage in clay-bearing rock repositories, shale gas extraction, and other uses of clay in the manufacturing industry. All the existing behavior models have restricted applications in the engineering and other fields of practice mainly due to the partial consideration of the structure and fabric of clay-bearing strata in the model formulation. In this study, a hydro-mechanical behavior model has been formulated using the parameters acquired from the molecular-level simulations and modeling of the volume change and stress–strain behavior of the clay-bearing structure. The Molecular Mechanics and Molecular Dynamic simulations were performed on the natural structure of the clay-bearing strata formulated using Monte Carlo technique. The mathematical model, developed from the simulation results, can predict the overall hydro-mechanical behavior of clay-bearing strata for all possible combinations of clay minerals, non-clay minerals, salts causing cementation of the soil/rock structure, confining pressures, and the induced strain levels. The developed model has successfully been validated through laboratory and field testing on the clay-bearing strata in both the elastic and elasto-plastic regions of the stress–strain behavior and also from the data of two (02) swelling clays (MX-80 and FEBEX Bentonite) from the existing literature, supporting the universal nature of the developed behavior model. [ABSTRACT FROM AUTHOR]

Discrete measurement targets were frequently utilized in image-based methods on the specimen's surface to monitor the soil specimen during triaxial testing. However, the required density of measurement targets that should be used in triaxial testing to achieve highly accurate volume measurement has not been investigated. To overcome this limitation, this paper presents a parametric study to determine the optimum target/point densities to be utilized on the triaxial soil specimen surface to achieve the desired level of volume measurement accuracy in image-based methods. LiDAR scanning was applied to establish the "ground truth" volume of the specimen. The effects of deformation and failure modes were investigated by calculating the volume measurement accuracy at different strain levels and for different undisturbed soil specimens of clay and sand with silt. An interpolation method was proposed to increase the number of discrete targets representing the triaxial specimen's surface. The analysis results show that a higher target density is required at a larger strain. Also, adding the number of interpolation points can only increase the accuracy to a certain level. As the volume measurement accuracy was different for each of the clay and sand with silt specimens, the non-uniform deformation, and failure mode of the specimen can affect the required optimum density of discrete measurement targets. In conclusion, it is recommended to choose the optimum density of targets based on the accuracy requirement, the maximum soil deformation level, and the expected failure mode of the specimen. [ABSTRACT FROM AUTHOR]

The Qingliucun mountainous area is characterized by steep terrain, large topographic variation, a considerable free face, and massive highly fissured clayey soils. A high landslide started on June 29 2020, rapidly evolving and eventually causing, on December 4, 2020, a global sliding mass to move downward rapidly. This event seriously damaged houses and the main mountainous road to Qingliucun village on the mountainous platform, and temporarily blocked the Mengtun River, causing a 100-m long dammed lake. This work introduces the main features of this landslide and the earlier results of studies on this event. The main geological characteristics of the site and the morphological features of the landslide are presented. Moreover, the failure mechanism of the landslide is revealed according to the outcomes of site reconnaissance and monitoring as well as limit equilibrium stability analysis. Finally, this work focuses on the empirical estimation of landslide runout distance, which is instrumental in the prevention and mitigation of similar high landslide hazards. [ABSTRACT FROM AUTHOR]

Compacted specimens prepared from four clayey soils were subjected to drying in order to monitor the volumetric shrinkage period. Specimen volumes were recorded with manual caliper readings and the proposed image-based method as the shrinkage continues. For the image-based method, a photogrammetry technique known as Structure from Motion was applied. This technique offers a complete three-dimensional solid model of objects from two dimensional images. In this technique, the object is photographed from different perspectives to construct a digital point cloud. Once a proper calibration is made, these points represent the real-world coordinates and comprehensive analyses can be made using surface data. To that end, an imaging setup was established and a parametric study was conducted on a solid calibration object for the accuracy assessment of the method. The volumes of the compacted specimens obtained with the image-based technique and conventional Vernier caliper readings were compared to each other and evaluations were made by means of volumetric strain graphs and soil shrinkage curves. The proposed shrinkage monitoring technique offered accurate, nondestructive and operator independent results. [ABSTRACT FROM AUTHOR]

Lasioglossum marginatum sp. is the most efficient pollinator of stone fruit crops (such as peach, plum, and cherry). Its proportional contribution to the total visitation is significantly higher than the conventional visitation. This species is polylectic, polyandrous, and an efficient pollinator that is endogeic in nature. Its nesting behavior has been studied earlier. Various nest soil physical characteristics like tumulus length, turret height, nest depth, nest density, nest diameter, nest length, and the height from the plane have been determined across the experimental sites and found to be statistically significantly higher than the normal range. Various parameters were found to be most significant in Budgam (Experiment location-I) located at an altitude of 1700 m above sea level (a. s. l.) higher than Srinagar (Experiment location-II) which is situated at an altitude of 1400 m a. s. l. The current study investigated some of the parameters like the total number of individuals per nest, cell length, cell diameter, cell area, sex ratio per nest, and the weight of pollen mass. Based on the Kolmogorov–Smirnov analysis outcomes, it was found that the species prefers clay loam soil. Further, various soil gravimetrical characteristics such as gravel/sand, slit, and clay in soils at different locations were significantly higher than the normal range. In addition to these, the Chi-square results regarding various nest soil chemical characteristics like the hydrogen ion concentration (pH), electric conductivity (dSm−1), organic matter (%), organic carbon (%), nitrogen (kg/ha), porosity (%) and soil moisture (%) content at different locations were significantly higher than the normal range. The maximum number of males emerged from the final brood in the 2nd—4th week of April; followed by the emergence of other workers and gynes, till the 4th week of May. The maximum flight activity was recorded from 15th April till the 1st week of May. The number of individuals per nest varied from 6 to 27 with a sex ratio in the range of 0.24 to 0.5. The minimum number of males and females per nest was found to be 1.0 and 5 respectively; while the maximum numbers were 9 and 18, respectively. The pollen-masses were found in short-side tunnels that were terminated with cells, in which the eggs were present and it sustained in the brood cells during the long overwintering periods. The current study helps in the conservation of bees by preserving their foraging plants and providing them with suitable and pollution-free breeding and nesting habitats. [ABSTRACT FROM AUTHOR]

Foundation plays a vital role in weight transfer from the superstructure to substructure. However, foundation characteristics such as pile group, piled raft, and footing remain unfolded due to their highly non-linear behaviour in different soil types. Bibliography analysis using VOSvierwer algorithm supported the significance of the research. Hence, this study investigates the load-bearing capacity of different types of foundations, including footings, pile groups, and piled rafts, by analyzing experimental data using finite element tools such as PLAXIS 2D and GEO5. The analysis involves examining the impact of various factors such as the influence of surcharge and the effect of different soil types on the load-bearing capabilities of the different types of foundation. For footing, parametric investigations using PLAXIS 2D are conducted to explore deformational changes. Pile groups are analyzed using GEO5 to assess their factor of safety (FOS.) and settling under various criteria, such as pile length and soil type. The study also provides insight into selecting the right type of foundation for civil engineering practice. Findings showed that different soil types have varying deformational behaviours under high loads with sandy soil having less horizontal deformation than clayey soil. Also, it was observed that increasing the pile thickness by 50% resulted in a reduction of 13.88% in settlement and an improvement of 16.66% in the FOS. In conclusion, this study highlights the importance of professionalism, exceptional talent, and outstanding decision-making when assessing the load-bearing capabilities of various foundation types for building structures. [ABSTRACT FROM AUTHOR]